Since this result assumes the downward approximation, the only contributing paths to a given vacuum \(I\)  are those given by a sequence of downward transitions. Thus the probabilities (REF ) favor vacua that can be accessed through downward transitions, from a large basin of ancestral vacua. Regions of the landscape with large probability must therefore have the topography of a deep valley, or funnel [1]}, [2]}, [3]}, [4]}. See Fig. REF . This is akin to the smooth folding funnels of energy landscapes of proteins [5]}. Naturally-occurring proteins fold efficiently because their free energy landscape is characterized by a smooth funnel near the native state.
